This invention relates to improved combustion chamber configurations for two-cycle engines. In particular the combustion chamber designs are for high pressure fuel injected systems requiring exaggerated chamber designs to insure a full and complete combustion that uniformly distributes the combustion forces over the head of the piston in a manner that maximizes the power stroke.
In short-stroke, high-compression engines that are fuel injected, there is little time in which to complete combustion. The injection process must therefore be precisely timed with the compression stroke to inject the fuel charge without premature combustion, but in a manner that fully mixes the injected fuel with the compressed air such that on auto combustion the advancing flame front rapidly consumes the fuel air mix without a damaging effect from the high pressure shock wave. In two-cycles engines having a mono valve exhaust system in which a single large valve is centrally located over the piston shock waves can be potentially damaging unless diverted from the central axis of the valve. Similarly, the center of the piston head is potentially a structurally weak spot that can be adversely affected by a symmetrically formed detonation and focused shock waves.
In similar prior art configurations, for example, as shown in Basabe, Pat. No. 2,658,487, issued November, 1953, entitled, combustion chambers partially isolated from the cylinder of the piston have been devised with configurations that produce turbulence patterns conducive to full and complete combustion. However, while the combustion chamber of Basabe is configured to develop the swirl and squish important to formation of a turbulence pattern that enhances combustion, the heart shape configuration of the resultant design does not fully protect the single exhaust valve from the peak pressures that are potentially dangerous to the structural integrity to the valve in a short stroke high pressure piston. Although the valve of the Basabe engine has a central prominence to divert the pressure front eminating from the piston head, the, prominence is insufficient to insulate the valve face from the pressure forces developed in an ultra-high pressure combustion.
The configuration described in Basabe is for a two-stroke internal combustion engine having a relatively long stroke and is particularly designed to develop jets of air into the combustion chamber at very high temperature so as to specifically enable ignition of the fuel without a very high degree of compression, and hence a very high mean effective pressure. Applicants, on the other hand seek to define configurations that will enable extraordinary high combustion chamber pressures without the destruction of either the piston head or, in those embodiments using mono-valve exhaust systems, the exhaust valve. To accomplish such, exaggerated configurations are employed to not only generate the annular turbulence pattern desired, but to protect both piston head and exhaust valve. In certain embodiments the combustion chamber configurations develop a double squish action to further enhance turbulant action.